This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. To continue our proposal work, the proposal number: GUP-8345 We propose to collect high resolution native and mutants data of the single-chain insulin. Home-source experiments (Raxix IV) diffract to 2.5 A resolution. We feel that the x-ray source at BioCARS will provide for better diffraction from small crystal. Insulin connecting peptide (C-peptide) aids the folding of single-chain insulin has been considered to have little biological activity. C-peptide has been shown to improve diabetic neuropathy and nephropathy as well as vascular inflammation. In vitro studies have reported that c-peptide may activate peroxisome proliferator-activated receptor-gamma, a nuclear transcription factor that plays a regulatory role in inflammation. this study was desiged to investigate the biological effects of c-peptide during endotoxemia. We expect to collect more set of diffraction data of single-chain insulin and mutants using synchrotron radiation and solve its crystal structure and study on the relationship od structure and function.